If you have 100 pills You have 10 bottles Each bottle weighs 1 gram You have 1 counterfiet it weighs 1.1 gram You can only use a scale to weigh one time Which one is the counterfit? Hint Number the bottles...

weigh each group, the heavy group cntains the culprit.
divide the heavy group into three sets, 2,2,1
compare the 2,2 group. If they areequal, the remaining bottle is bad.
If they are unequal, the heavy group of 2 contains the culprit.
compare those two.